The Supreme Court's 1961 decision in the case of Mapp v. the State of Ohio was in favor of the petitioner, Dollree Mapp.

Mapp was arrested, tried, and convicted for possession of pornographic material in her home in Cleveland, Ohio in 1957. When the Cleveland police officers entered her home, they did so on the pretense of searching for a bombing suspect. When Mapp refused them entry into her home, some of the officers departed, only to return later with a piece of paper they claimed was a valid search warrant. They refused to let Mapp read the "warrant," and, when she grabbed the piece of paper out of an officer's hand, she was forcibly restrained, her house searched, the pornographic material found, and she was arrested.

The State of Ohio, which tried Mapp on the pornography charge, was acting contrary to both the words and the intent of the Constitution.

The Supreme Court ruled that the police acted improperly, and violated Mapp's Fourth Amendment right against "unreasonable searches and seizures." The police lacked probable cause to request a warrant, did not demonstrate that they had a warrant, and seized material from Mapp's home completely unrelated to the stated purpose for wanting to search the house to begin with. In its decision, the Court wrote that "...all evidence obtained by searches and seizures in violation of the Constitution is [under the Fourth Amendment], inadmissible in a state court."